Technical Field
The present disclosure relates generally to detecting and measuring physical activity. More particularly, the present disclosure relates to a wearable metabolic physical activity monitor and associated methods.
Background Information
Obesity resulting in coronary heart disease and type 2 diabetes is a serious epidemic threat to the health of the population in almost every country of the world. Despite the genetic susceptibility of some individuals, the principal reasons for these medical problems are the unhealthy diets and sedentary lifestyles of the population at large. National campaigns educating the population of the risk factors and the need for a healthy diet and exercise are a high priority but, as yet, have not had a meaningful impact on obesity related disease. Education about healthy diets and monitoring food-calorie intake has been promoted by many private and government entities. In fact, food product labeling is mandatory in the United States and Europe and is increasingly being implemented in Asia and Latin America. Furthermore, health-conscious public and private organizations have recommended physical exercise, in addition to a healthy diet, as being critical for weight control programs. Unfortunately numerous profit-motivated organizations, both well-meaning and dubious, have promoted questionable rapid weight loss programs, unsubstantiated supplements and similar fad weight-loss programs.
Making healthier diet choices has met with some success, but the adoption of physical exercise on a routine basis has proved to be more challenging. Daily physical activity is essential to defeating obesity related diseases but weight loss programs fall short in persuading people to adopt a consistent physical exercise program. A major reason for such failures is that individuals are not able to track their efforts and receive immediate feedback. As a result, many computer and smart phone software programs have appeared that allow the user to track their food intake and calorie expenditure during exercise. Many individuals have found this to be a successful strategy for losing and maintaining weight. However, there are serious shortcomings to using this strategy for tracking calorie expenditure.
These include the inconvenience of manually keying in information for each individual physical activity and more importantly, the inherent inaccuracies of using generalized look-up lists of calorie expenditure values. The lists are based on estimates of an average person doing that activity. In actuality, there is so much variation between people that actual values for individuals are often vastly different when compared to the lists.
Personal wearable fitness monitors including wristbands, watches and even clothing have recently been introduced in an attempt to individualize and provide better calorie expenditure estimates. They add convenience because the monitors may include their own electronics, display and wireless connectivity and have the ability to connect to a smart phone or other computing device, allowing calorie expenditure to be calculated and recorded automatically. Fitness monitoring devices usually track movement with some type of movement instrument such as an accelerometer. Although accelerometer or similar instruments are fairly accurate when monitoring walking, running or sleeping, they are notoriously inaccurate when quantifying movement with other popular exercises. For example, racquet sports, skiing, yoga, weight lifting, tai chi and aerobics create various movement signals from the accelerometer but expended calorie values are unreliable because the device readings are calibrated to walking/running. Also, readings with accelerometer based fitness monitors are highly variable, even when measuring the same exercise activity, because readings depend both on the user's individualities and the physical placement of the device.
Typically monitors often use accelerometers or magnetometers attached or incorporated into a variety of wristbands, wrist and other watches, ankle bracelets or chest bands. The expended calories value is based on the accelerometer readings, together with providing the individual's age and weight. Thus, calorie expenditure values are commonly calculated for an average person of a certain gender, weight and height. For this reason, they are not actual values for a specific person but an estimate based, at best, on limited population studies (usually in Western Countries).
In reality, a large number of individual variables may influence the true expended-calorie value for a given exercise physical activity for a specific person. An individual's genetic makeup, BMI (body mass index), body composition, diet, medications and ingested supplements together with their underlying BMR (basal metabolic rate) all contribute to the number of calories being expended. Many devices use estimates of these values based on the average person. Assumptions are inaccurate for individuals in many cases. Although walking and running calorie expenditure may be approximated with accelerometer-based monitors, the same is not true for other physical activities depending on the type of exercise and body placement of the accelerometer. Because calorie expenditure is so individualized, the assumptions underlying the calculations based on accelerometer readings are valid for only a limited segment of the population.